Suspicious WMI Image Load from MS Office

Elastic Stack Serverless Security

Identifies a suspicious image load (wmiutils.dll) from Microsoft Office processes. This behavior may indicate adversarial activity where child processes are spawned via Windows Management Instrumentation (WMI). This technique can be used to execute code and evade traditional parent/child processes spawned from Microsoft Office products.

Rule type: eql

Rule indices:

• winlogbeat-*
• logs-endpoint.events.*
• logs-windows.*

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References:

• https://medium.com/threatpunter/detecting-adversary-tradecraft-with-image-load-event-logging-and-eql-8de93338c16

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Execution

Version: 5

Rule authors:

• Elastic

Rule license: Elastic License v2

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate event.ingested to @timestamp for this rule to work.

library where process.name : ("WINWORD.EXE", "EXCEL.EXE", "POWERPNT.EXE", "MSPUB.EXE", "MSACCESS.EXE") and
  event.action : "load" and
  event.category : "library" and
  dll.name : "wmiutils.dll"

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Execution
  • ID: TA0002
  • Reference URL: https://attack.mitre.org/tactics/TA0002/

• Technique:

  • Name: Windows Management Instrumentation
  • ID: T1047
  • Reference URL: https://attack.mitre.org/techniques/T1047/